Failed to execute goal org.apache.maven.plugins:maven-jar-plugin:2.4:jar (default-cli) on project piu-commandline: Error assembling JAR code example

Example: Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile) on project electronicbookshop: Compilation failure

<plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>2.4</version>
            <configuration>
                <source>1.8</source>
                <target>1.8</target>
</configuration>
</plugin>